Method of securing accurate color values in color printing and color photography



Dec. 23, 1930.

c. BLECHER l ,785,997

METHOD OF SECURING ACCURATE COLOR VALUES IN' COLOR PRINTING AND COLOR PHOTOGRAPHY Filed July 28, 1925 Patented Dec. 23, 1930 UNITED -.s-rA'1ss4 'PATENT OFFICE CARL B LECHER, OF `IBERLIN-DAELEI, GERMANY METHOD OF SECURING ACCURATE COLOR VALUES COLOR PRINTING AND COLOR PHOTOGRAPHY Applicationnled iul'y as, uwas, semi No.

The object of this invention is to indicate a way, in which in the process of making printing copies for photographic, intaglio, lithographie or combnationprintin in co1- ors, and in the makingof negatives tor color photography the accurate reproduction of the 'colorsmay beobtained with certainty, without it being necessary in the case of the color print-ing processes referred to above.

to prepare preliminary' prints orr inthe case of color photo aphy to make a trial copy.

The path to i; pursued differs according to whether for the purpose of color printing or color photography there is a series of part negatives 4or only a single negative, whereas the idea of the' present invention is used in both ways.

For carrying use the arrangement shown in the drawin representing by Way of example one embodiment, in whlch: y Figure 1 is a lower inner plate having a colored film layer; 1

Figure 2 is an outer plate to be placed over it;

Figure 3 is the outer upper plate to be placed over' the late of Figure 2;

Figure 4 is t e upper inner plate to be placed into the latter;

Figure 5 shows a general plan of the plates of Flgure'l-et screwed (attached) to a base late p Figure 6 is a section along 'VI-VI of Figure 5; and

Figures 7,8 and 9 show the attaching means drawn to an enlarged scale. When a series of art negatives is -to be dealt with, this isveffected in the following manner:

fixing them to the latter for instance by means of suitable adhesives, such as nitrocellulose solutions, gelatine'solutions or the like. Such thin stuck-on films cannot warp and, owing to their being -so thin are practically colorless, so that the color of the film material itself, which in the case of thick films would be detrimental'for the purpose of the present process, has no bad effect. The stretched film n n@ Hw further advantage that. owing to the rigidity,

out the invention one may vsilver images. Aare to be preferred. Tie obtained part Thin films are stretched on frames by af-` many ,cases be 4e,aes, anun Germany august no, im.

,Y of the supportin frame, it can very easily e treated in the orizontal position with the requisite sensitive layer for producing the part negatives. This renders it unnecessary to keep in stock a material for formin the sensitive layer which may be of unsuita le color, and the co oring of the layer may be given the desired nuance in eachl case. On thel stretched films intermediate copies are made in the required'colors. Copies may be made for all the colors on thin'stretched'` films or the bottom colored part image may be copied on opal glass, white non-extensible paper, white Celluloid or' the like. When this is not done, all 'the Vco ies made on films must be superposedv on eac other in register` on'a white refiecting support. If, on the other hand, the bottom image mav be made on a white support and affixed to the same, this support together with the bottom part image thereon is laid under the copies on thin stretched' films of the part negatives, which` are superposed in register with one another. AIt is immaterial how the bottom copy and howother copies on films are ro-v duced. The copies 'may be colored re iefs obtained by dissolvin out or may be toned For b ack ure silver images images are superposed on one another' in the order, in which the a're to be subsequently united to form tl; finished picture,l as stated above either only on a white reflecting support or they are laid on the bottom colored art image. "By the superposiss tionof the lms with the part copies it `becomes possible to Ivcompare the multi-colored total effect of this composite picture with the multi-coloredv picture .to be roduced by printing or photographically. f the total effect is correct, nothing-will haveto be valtered in the negatives. If, however, the composite picture should not be found Vto be correct, the negative will have to be suitably retouched and, when this has been done, fresh copies of the retouched negatives made. If the part images so obtained are to be hotographed, as explained below, it wil in ireferable to work over the colored interme ate image in-its own colorr used in When not a series of half-tone negatives' are used, but a single half-tone negative for producing a multi-color image, an intermediate image is made from this negative in the form of a copy for one color. This'copy may be placed on a stretched film and the latter be provided with a white, reflecting support, or the copy is placed directly on a copying layer on a white support.` This partial image provides the outlines. On to this partial image are placed thin films, which are stretched 011 frames without images and on to these films the remaining desired part images (intermediate images) are drawn.

For making the drawing the same color is of' course used, in which the drawn4 partial image is to be printed or copied. It would also appear to be possible to place on the stretched films colorless copies of the single lialf-tone negative and to color the same selectively in the particular colors which the part images are to have. Just as the part images on films, made by copying are superposed in suitable order for the purpose of ascertaining the general effect of the multicolor image, those produced by drawing are superposed for the same purpose and are eX- amined over a white reflecting support. If the general impression either of the superposed copies or drawings is satisfactory, it will not be necessary to make alterations of any kind either on theoriginal negatives making the copies or on the part images themselves.

As already pointed out, such thin films are used for stretching on the frames that the color of the film material shall in n o case affect the-appearance of the composite image, which gives perfectly pure color values. When more than two colored part images (obtained either by copying or drawing) which are on thin stretched films have to be superposed on one another on the reflecting white support, it is necessary that the frames for the films shall be of different size, such that they may be `placed one in another.

It is assumed that in composing (producing) the colored picture, one starts with the four fundamental colors, yellow, red, blue and black, and that these four color shades are to be separately copied as film negatives which are to be superposed so that a composite picture is obtained containing the individual color shades in the right proportion.

In the example indicated, the arrangement it is in general much easier to in# includes four frames la, 1b, 1c, lol, to which are attached the colored copied films 2a, 2b, 20 and 2d. On the film 2a the yellow field 3a is copied, on the film 2b the red field 8b, on the film 20 the blue field 3c, and on the film 2d the blackfield 3d, and in such a manner that the color fields 3a, 3b, 3c and 3d follow each other from right to left with the super- `imposed films 2a, 2b, 2c and 2d. For the sake of clarity, the color fields are not superimposed here, since they are recognizable by the intermediate shades resulting from the superimposed colorsv and may be readily understood, as in this example stress is laid only on an explanation of the manner of carrying out the process.

The frame la fits exactly in the frame 1b and the frame 1b in the frame 1c. rIhe frame la has an abutting projection 5a having two holes 6a and the frame 1d has two holes 6d, whereas the frames 1b and 1c have at their sides facing each other the projections b and 5c respectively. The abutting projections and holes serve to fix the frames in a manner to be described hereafter. The frames la, 1b and 1c have, in addition, reenforcing ridges 4 placed at some distance from the inner and outer ends, whereas the frame 1d is flat. The color fields 3a to 3d are each arranged inside of a bounding line c', c, 0" and 6 and these bounding lines are congruent. The frames represented in Figures l to 4 are so superimposed that the frame la lies below and it is so placed with its upper film layer 3a on a table 2l, which carries a white reflecting surface 27, for instance a porcelain plate, that the film layer 3a lies fiat on the white reflecting base 27 and the frame la hangs freely, for which purpose the table 2l is higher than the edge 4 of the frames la, lb, as is seen in Figure 5. The

`bottom plate 22 serves as the fixing device for 'layer 2a. There is then placed on the frame l?) the frame l0 and in such a manner that the film layer 20 lies directly on the film layer 2b and the edge 4 is turned upwards Finally, the frame 2d is placed again with its film layer turned downward in the clear opening of the frame 20, so that it too rests directly on the layer 20, and all four layers 2a to 2d lie closely upon each other as is apparent from Figure 5, and thus reproduce the correctly assembled composite picture, when the four bounding lines o to 0 of the films 2a to 2d cover each other. In order to be able to arrange the picture precisely, some space (play) is left between the inner dimens-ions of the frames la, 1d and the outer dimensions of the frames 1b, le, so that the frames la, 1d may be somewhat displaced in the frames 1b and 1c. Four brackets 9 may be fixed on Yinsister the base plate 22 by means of screws 10, wing nuts 11 and Washers 11, which may be displaced a certain amount in all directions inside the openings 12, and which carry a vertical post 13, having in its center a longitudinal slot 14: open above. Bolts 15 are inserted in these slots 14, carrying at one of their ends a pin (tommy) 16 and at their other end a screw thread on which is threaded a wing nut 17. In addition, each bracket 9, respectively its post 13, is provided with a guide 18 and a projection 19, whereby the guide 18 fits into triangular grooves 18, Which'are correspondin ly provided on the projections 5b, 5e and 13 of the plates 1b, 1c as well as on the connecting members 7a and 7 d. The superposed lates lez- 1d are attached by means of the racket 9 with the base plate 22 and are thus fixed with regard to each other. Thereupon the plate la is fixed in a manner similar to the superposition of the plates let- 1d with the upper bracket 9 of the base plate by means of a connecting member 7 a, that contacts by means of pins 8 in the slots 6a of the plate 1a, and which is bent downwards (Figure 8) so that the pin (tommy) 16 lits behind the projection 13 of the connecting member and the projection 13 of the connect-ing member is drawn on tightly against the post 13 of the bracket 9 by means of the wing nut 17. The guide 18 and the projection 19 thereby rigidly` fix the connecting member 7 a and as a result the plate 1a on the base plate 22. An opening 20 is provided in the base plate 22 for the passage of the connecting member 7a (Figures 5 and 6). The plate 1b, the right molding of which is somewhat wider than the rest, is thereupon so arranged that the bounding line c covers the bounding line c', the bracket 9 being then screwed on in the manner ldescribed with regard to the plate la directly against the projection 5b, and the nuts 11 of the bracket being drawn on tightly so that the plates 1a, 1b are fixed so that they cannot be displaced. Thereupon the plate 1c, the left side of which is wider than the rest, is then arranged in a manner similar to the plate 1b, and is fixed. whilst the nlate 1b is again screwed on against the bracket 9 by means of a connecting member 7d which is bent at 7 and is fixed .by it on the base plate 22, whereby the pins 8 of the connecting member 7 d whlch penetrate into the openings 8d are directly upwardly.

The bounding lines c to 0 now cover each other and the composite picture is disposed in accordance with its color arrangement, so that it may be used as a unit when the nuts 11 and 17 are drawn on tightly. In Figures 7 and 9', there is shown to an enlarged scale how the guides 18 and the projections 19 are placed respectively against the projections b, 5c and 13 of the plates 1b and lo respectively of the connecting members 7a, 7d, whereby there is insured on account of the semi-circular shape of the guide 18, a certain and definite mounting in the groove 18. The plate ldmay be pressed with its free end upward and tightly against `the lower plates by means 'of afixed bolt 23, arranged in the base plate 22, to which is fastened, b means of a nut 24, the attachable arm 2.5` aving a set screw 26. f y

If the individual colors of a picture, which is to be put together by means of fundamental colors, are more or less distributed over the whole surface of the film layers inside the inner dimensions of the frames 1a and 1d, there result then at the places, where the different colors are superposed one or Vmore times, the correct intermediate shades (tones), upon which are modeled the retouches Von the printing plates. i

Should the multi-color composite image produced by superposing the stretched films carry-ing the separate partial images give the correct color.v impression, nothing more need be altered onv the part negatives, as stated above, in soft-ar as they can be used directly for the purposes of color printing or color photography. If, on the other hand, only a single outline negative and a copy made with it, While the remaining part copies have been produced by drawing, or in those cases, in which the'image to' be produced by printing or photographically is to be aV reduction or enlargement of the negative or negatives used, the procedure is as follows:

From the image on the stretched films or prepared for the bottom part image, which may be on a white, reflecting support halftone or -screen negatives in the required sizes are made successively in plan photographically with or `without color filters, the copies or drawings on the films being provided with White supports. The operator is quite free to adjust the gradation and size of the negatives to be made to any desired value. Hence, the use of the negatives made either for the production of forms for color printing or for the purposes of color photography does not entail special difficulties. In this respect the methodA according to the present invention diers considerably and very advantageously from the earlier method, in which intermediate images (intermediate positives) were also used. In the earlier method the color values were controlled by black and white retouching. In the new method the image is presented to the observer in its full color effect more or less accurately. The color effect is lirst corrected and only after this has been done are the negatives for copying purposes made.

I claim l. A method for securing accurate color valuesin color printing and color photography, ,characterized by the feature that for the colored part images to be placed together intermediate images are made in the respective colors on thin films stretched on frames.

2. A method of securing accurate color values in color printin and color photography, characterized by t 1e feature that for the colored part images to be laced together intermediate ima es are ma e in the respective colors on thin lms stretched on frames, the separate frames for the different part images being of different size and adapted to be placed one in the other.

3. A method of securing accurate color values in color printing and color photography, characterized by the feature that for the colored part images to be placed together intermediate images are made in the respective colors, the intermediate images, when being copied, being made with a shorter gradation than is to be shown by the finished colored part image.

4. A method of securing laccurate color values in color printing and color photography, characterized by the feature that for the colored part images to-be placed together intermediate images are made in the respective colors on thin ilms stretched on frames and are photographed with a white reiecting support placed under them.

5. A method of securing accurate color values in color printing and color photography, characterized by the feature that an intermediate image, which lies at the bottom and is already on a White support, s photographed to the same size as the intermediate images on thin films stretched on frames and having a white reflecting support under them.

In testimony whereof I hereunto affix my signature.

CARL BLECHER. 

